ATBECHDEDKESFRGBGRITLILUNLSEMCPTIESILTLVFIROMKCYALTRBGCZEEHUPLSK..HRIS..MTNORSMESM..................J0009210-RPUB024253336EUROPEAN PATENT SPECIFICATIONB120250521EP23000048.12023032720240327enenen20221101936720220331IN20250521202521202310042023402025052120252120240902

C03B 37/027 20060101AFI20230817BHEP

C03B 37/029 20060101ALI20230817BHEP

C03B 37/03 20060101ALI20230817BHEP

C03B 37/029 20130101 FI20230807BHEP

C03B 37/027 20130101 LI20230807BHEP

C03B 37/02718 20130101 LI20230807BHEP

C03B 37/032 20130101 LI20230807BHEP

C03B2205/04 20130101 LA20230807BHEP

C03B2205/56 20130101 LA20230807BHEP

C03B 37/02727 20130101 LI20230807BHEP

deBIEGEN VON GLASFASERN IN EINEM TÜRM UND DAZUGEHÖRENDER VORRICHTUNGenIN-TOWER OPTICAL FIBER BENDING AND ASSOCIATED APPARATUSfrFLEXION DE FIBRE OPTIQUE DANS UNE TOUR ET APPAREIL ASSOCIÉJP-A- 2013 203 623US-A1- 2019 256 400Badri, GomatamGurugram, Haryana, 122102INSterlite Technologies Limited101988557P-2023-671 EP15th & 16th Floor Capital Cyberscape,Sector 59Gurugram, Haryana 122102INValet Patent Services Limited102057897c/o Caya 83713X Am Börstig 596052 BambergDEALATBEBGCHCYCZDEDKEEESFIFRGBGRHRHUIEISITLILTLULVMCMEMKMTNLNOPLPTRORSSESISKSMTR TECHNICAL FIELD

Embodiments of the present disclosure relate to the field of optical fiber manufacturing equipment and more particularly, relates to an optical fiber draw tower facilitating in-tower optical fiber bending and an optical fiber processing method.

Background Art

With the progress of communication networks in recent years, optical fiber communication networks have been rapidly developed. Optical fibers are useful in a wide variety of applications, including the telecommunications industry for voice, video, and data transmissions. Currently, a demand for reducing the manufacturing cost of an optical fiber is ever increasing, in addition to an improvement of optical transmission characteristics of the optical fiber.

In recent years, significant advancements have been made in the manufacture of optical waveguide fiber, which in turn have increased the usable light carrying capacity of the fiber. However, it is well known that electromagnetic radiation traveling through an optical waveguide fiber is subject to attenuation or lose due to several mechanisms. Although some of these mechanisms cannot be reduced, others have been eliminated, or at least substantially reduced.

Manufacturing methods for producing optical fibers typically include drawing optical fiber from a glass perform that is heated in a draw furnace, cooling the drawn fiber, and coating the fiber after it has sufficiently cooled. However, the process parameters employed by the fiber manufacturing process may have a significant impact on the resultant performance characteristics of the drawn fiber. During optical fiber manufacturing, glass preforms are heated at a high temperature significantly above the softening point of the glass and drawn at a high draw down ratio and a high draw speed to produce an optical fiber due to which the glass preforms do not reach an equilibrium state. This results in the production of optical fiber with high fictive temperature, which is undesirable as it results in increased attenuation, i.e. signal loss.

One way to address the aforesaid drawbacks is modifying fiber processing conditions that can allow manufacturing the optical fiber with lower fictive temperature. Efforts to reduce fictive temperature have emphasized slow cooling to stabilize the optical fiber in a state closer to an equilibrium state. Prolonged cooling of an optical fiber at temperatures in the glass transition range of the fiber is another strategy for reducing fictive temperature.

US patent application no. US20190256400 titled "Low attenuation optical fiber" discloses an optical fiber with low attenuation. In particular, the optical fiber is produced under conditions that reduce fictive temperature.

US patent application no. US10696580B2 titled "Optical fiber with low fictive temperature" discloses an optical fiber with low fictive temperature along with a system and method for making the optical fiber.

WIPO patent application no. WO2014046274A1 titled "Optical fiber fabrication method" discloses a method in which the fictive temperature is sufficiently reduced to fabricate an optical fiber with low loss and high yield.

US patent application no. US6565775B2 titled "Method of cooling an optical fiber while it is being drawn" discloses a method of cooling an optical fiber during drawing through contact with at least one cooling fluid in at least one cooling area. In particular, the temperature profile of each cooling area is established so that the fictive temperature of a cladding of the optical fiber is maximized, and the fictive temperature of a core of the optical fiber is minimized.

However, there are a number of drawbacks in the current technologies for manufacturing optical fibers with lower fictive temperature. In particular, the fictive temperature is not reduced to a satisfactory/desired level by the currently used manufacturing methods due to a short residence time. Subsequently, the structure of the glass preforms does not reach a required equilibrium state as the decrease in the fictive temperature is small. Moreover, the existing manufacturing methods utilize a turn or fold mechanism and mechanically move the path of the draw outside the draw tower assembly. As a result, the optical fiber cannot be drawn within required fictive temperature and attenuation values without dimensionally changing the existing draw tower set-up. This, in turn, makes the fiber drawing process costly due to the requirement of additional equipment.

Furthermore, conventional slow-cooling techniques do not optimize the temperature history of the optical fiber in a predetermined range. As a result, such conventional slow-cooling techniques may not efficiently reduce attenuation in the optical fiber, and may degrade productivity, because a heating furnace for slow cooling may become unnecessarily long, or a drawing speed may become slow to ensure a long slow-cooling time.

Therefore, there exists a need for an improved technique which solves the aforesaid drawbacks and allows easy manufacturing of optical fibers in restricted space (i.e., within an available volume of the draw tower) without encroaching outside space of the draw tower and with increased residence time and reduced fictive temperature and attenuation.

Accordingly, to overcome the disadvantages of the prior arts, there is a need for a technical solution that overcomes the above-stated limitations in the prior arts. The present disclosure provides a method for conveniently manufacturing optical fibers in restricted space or within an available volume of the draw tower, without encroaching the outside space of the draw tower and with increased residence time and reduced fictive temperature and attenuation.

SUMMARY OF THE DISCLOSURE

According to the invention, the present disclosure provides an optical fiber draw tower configured to melt a preform into an optical fiber , the optical fiber draw tower including a top end zone and a bottom end zone, a preform inserted at the top end zone and is melted into the optical fiber that exits from the bottom end zone and a plurality of air knives that distorts an optical fiber path such that partially uncooled optical fiber deviates from a vertical path and follows a bended path. In particular, a fluid is inserted into the optical fiber draw tower from the top end zone .

According to the invention, the bended path length is greater than a vertical path length. And., the bended path length is defined by laminar flow for at least 70% of the bended path length.

According to the invention, the plurality of air knives is a plurality of openings arranged such that to cause distortion on the vertical path of the optical fiber in the optical fiber draw tower . In particular, the plurality of openings is a combination of one or more of a suction and pumping of the fluid. Moreover, the plurality of air knives modifies mass flow of the fluid in a predefined manner to modify the optical fiber path inside the optical fiber draw tower .

In accordance with an embodiment of the present disclosure, the plurality of air knives is arranged such that the fluid enters or exits the optical fiber draw tower at an angle of 0-89 degrees with respect to the vertical path.

According to another aspect of the present disclosure, the bended path length is at least 10% greater than the vertical path length of the optical fiber .

In accordance with an embodiment of the present disclosure, the bended path length for a single partial turn.

In accordance with another embodiment of the present disclosure, the bended path length for multiple partial turns.

In accordance with an embodiment of the present disclosure, the bended path length for multiple partial turns.

According to the invention, the present disclosure provides a method of drawing an optical fiber in an optical fiber draw tower comprising steps of drawing the optical fiber from a preform and modifying a vertical path length of the optical fiber by subsequent partial turns. Particularly, the bended path length is defined by laminar flow for at least 70% of the bended path length, thereby modifying the vertical path length of the optical fiber into the bended path length.

According to the invention, the method includes modifying the vertical path length of the optical fiber by the subsequent partial turns. A further aspect comprises applying external force to uncooled optical fiber at one or more predefined zones in the optical fiber draw tower ; and altering path of a fluid at the one or more predefined zones in the optical fiber draw tower due to application of the external force causing the uncooled optical fiber to deviate from the vertical path into a bended path.

According to another aspect of the present disclosure, the method further includes applying the external force to the uncooled optical fiber comprising at least one of adding or removing fluid mass from the optical fiber draw tower in the one or more predefined zones such that the optical fiber bends subsequently in partial turns, thereby modifying the vertical path length to a bended path length.

The foregoing solutions of the present disclosure are attained by employing an optical fiber draw tower facilitating in-tower optical fiber bending and a processing and drawing method thereof.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the present disclosure or in the prior art more clearly, the following briefly describes the accompanying drawings required for describing the embodiments or the prior art.

Fig. 1 is a snapshot illustrating an optical fiber draw tower in accordance with an embodiment of the present invention;
Fig. 2 is a snapshot illustrating an exemplary illustration showing a single partial turn for an optical fiber in accordance with an embodiment of the present invention;
Fig. 3 is a snapshot illustrating exemplary illustration of multiple partial turns for the optical fiber in accordance with an embodiment of the present invention; and
Fig. 4 is a flowchart illustrating drawing the optical fiber in accordance with an embodiment of the present invention.

The optical fiber draw tower is illustrated in the accompanying drawings, which like reference letters indicate corresponding parts in the various figures. It should be noted that the accompanying figure is intended to present illustrations of exemplary embodiments of the present disclosure. This figure is not intended to limit the scope of the present disclosure. It should also be noted that the accompanying figure is not necessarily drawn to scale.

DESCRIPTION OF EMBODIMENTS

The disclosure also includes all such steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.

Definitions:

For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are collected here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.

The articles "a", "an" and "the" are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

The terms "comprise" and "comprising" are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as "consists of only". Throughout this specification, unless the context requires otherwise the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps.

The term "including" is used to mean "including but not limited to". "Including" and "including but not limited to" are used interchangeably.

The following brief definition of terms shall apply throughout the present disclosure:
The ITU.T, stands for International Telecommunication Union-Telecommunication Standardization Sector, is one of the three sectors of the ITU. The ITU is the United Nations specialized agency in the field of telecommunications and is responsible for studying technical, operating and tariff questions and issuing recommendations on them with a view to standardizing telecommunications on a worldwide basis. The optical fiber may be a bend insensitive fiber that has less degradation in optical properties or less increment in optical attenuation during multiple winding/unwinding operations of an optical fiber cable.

In opening, simultaneous reference is made to Fig. 1 through Fig. 3, in which Fig. 1 is a snapshot illustrating an optical fiber draw tower, Fig. 2 is a snapshot illustrating an exemplary illustration showing a single partial turn for an optical fiber, Fig. 3 is a snapshot illustrating exemplary illustration of multiple partial turns for the optical fiber in accordance with various embodiments of the present disclosure.

The optical fiber draw tower 100 may also be referred to as a draw tower. In particular, the optical fiber draw tower 100 is configured to melt a preform 104 into an optical fiber 106 and is defined by a top end zone 108 and a bottom end zone 110. The preform 104 is inserted at the top end zone 108 and is melted into the optical fiber 106 that exits from the bottom end zone 110. Moreover, the temperature at the top end zone 108 is in the range 950 to 1050 degree Celsius and the temperature at the bottom end zone 110 is in the range 750 degree Celsius to 800 degree Celsius.

In accordance with an embodiment of the present disclosure, the preform 104 is a glass preform i.e., silica preform.

The optical fiber 106 refers to a medium associated with transmission of information over long distances in the form of light pulses. The optical fiber uses light to transmit voice and data communications over long distances when encapsulated in a jacket/sheath. The optical fiber may be of ITU.T G.657.A2 category. Alternatively, the optical fiber may be of ITU.T G.657.A1 or G.657.B3 or G.652.D or a multi-core or other suitable category.

The fluid inserted into the optical fiber draw tower 100 from the top end zone 108 may be liquid or air or N2 (nitrogen) or other suitable fluid.

In accordance with an embodiment of the present disclosure, the optical fiber draw tower 100 comprises, but not limited to, a preform insertion device 102 and a plurality of air knives 112. The preform insertion device 102 may also be referred to as a preform holding device. Particularly, preform insertion device 102 is configured to hold and insert the preform 104 inside the optical fiber draw tower 100 and is installed near the top end zone 108 of the optical fiber draw tower 100.

The plurality of air knives 112 is a plurality of air bearings arranged along with height 124 of the optical fiber draw tower 100. In particular, the plurality of air knives 112 is configured to distort an optical fiber path such that partially uncooled optical fiber deviates from a vertical path and follows a bended path as shown in Fig. 1, where the vertical path is defined by gravitational force and a bended path length is greater than a vertical path length.

In an exemplary example, the bended path length is at least 10% greater than the vertical path length of the optical fiber 106, leading to at least 10% increase in residence time of the optical fiber 106.

Typically, residence time is the total time that the optical fiber 106 has spent inside the optical fiber draw tower 100. Further, the bended path length is defined by laminar flow for at least 70% of the bended path length.

In accordance with an embodiment of the present disclosure, the plurality of air knives 112 is configured to guide semi-cooled fiber in a non-linear path in a vertical resultant fiber draw direction. The plurality of air knives 112 includes a plurality of openings arranged such that to cause distortion on the vertical path of the optical fiber in the optical fiber draw tower (100). Moreover, the plurality of openings is a combination of one or more of a suction and pumping of the fluid. Further, the plurality of openings of either pump-in and suck-out fluid causes distortion in fluid flow path, while maintaining the laminar flow, which causes increase in path length without increasing space requirements.

In accordance with an embodiment of the present disclosure, the plurality of air knives 112 are arranged such that the fluid enters or exits the optical fiber draw tower 100 at an angle of 0-89 degrees with respect to the vertical path.

Particularly, the plurality of air knives 112 modifies mass flow of the fluid in a predefined manner to modify the optical fiber path inside the optical fiber draw tower 100 and exerts a force to displace the optical fiber 106 of mass less than 37 km for 1 kg glass, where the optical fiber 106 may have a diameter of 250 microns or less. Further, the plurality of air knives 112 modifies the vertical path length taken by the optical fiber 106 (in melted state) due to gravity by subsequent partial turns as depicted in FIG. 1.

Such modification in the vertical path length is done by applying external force to the optical fiber (uncooled optical fiber) at one or more predefined zones 114, 116, 118 in the optical fiber draw tower 100 and by altering path of the fluid at the one or more predefined zones 114, 116, 118 in the optical fiber draw tower 100 due to application of the external force which causes the optical fiber in uncooled state to deviate from the vertical path into the bended path. The external force to the optical fiber in uncooled state is applied by at least one of adding or removing fluid mass from the optical fiber draw tower 100 in the one or more predefined zones 114, 116, 118 such that the optical fiber bends subsequently in the partial turns.

In accordance with an embodiment of the present disclosure, the plurality of air knives 112 guides the slanted path along with gravity. In particular, the optical fiber 106 drawn from the preform 104 is conveyed through the plurality of air knives 112, where a first air knife from the plurality of air knives 112 directs the optical fiber 106 to a second air knife, the second air knife directs the optical fiber 106 to a third air knife and so on so forth. In other words, the optical fiber 106 is directed from a first set of air knives of the plurality of air knives 112 to a second set of air knives of the plurality of air knives 112 that facilitate controlled cooling of the optical fiber 106. The optical fiber 106 is directed from the first set of air knives to the second set of air knives in an alternate manner and at predefined angles such that a bending angle of the first set of air knives is different than a bending angle of the second set of air knives that results in multiple partial turns 120 to the optical fiber 106.

In accordance with an embodiment of the present disclosure, the multiple partial turns 120 are step turns in a sequence, which may be implemented between 10-90 degrees in the optical fiber draw tower 100. Advantageously, sum of partial turns increases the residence time of the optical fiber 106. The multiple partial turns 120 can be achieved by optimizing fluid flow with the optical fiber draw tower 100, where the fluid flow in the optical fiber draw tower 100 is directed from top to bottom. One example of optimization technique includes use of multiple inlets and outlets (i.e., the plurality of openings) along the height 124 of the optical fiber draw tower 100 for the fluid flow. Other optimization techniques may also be used.

Due to the aforementioned arrangement, the length of the optical fiber 106 exiting a turn is +1 the length of optical fiber 106 entering the turn. For the same, referring to Fig. 2 and Fig. 3 depicting the single partial turn and multiple partial turns 120 respectively, which is further explained below using equations:

Equation 1 - Bended path length for the single partial turn: $\begin{array}{l} OA = OU = OQ = r \\ AQ = 2 Δ = 2 r \cos \cos θ \end{array}$ Where A = entrance path of the optical fiber shown using reference numeral 202 and Q = exit path of the optical fiber shown using reference numeral 204.

Equation 2 - Bended path length for the multiple partial turns 120 within an idealized tower frame border, i.e., available tower width 308: $\begin{array}{l} \sum_{i = 1}^{N} h_{i} + \sum_{i = 1}^{N} Δ_{i} = H_{T} \\ \sum_{i = 1}^{N} L_{i} = H_{T} (1 + p) \end{array}$ Where p = desired fractional increase in draw path length, N = number of turn segments required to cover a vertical drop 304 and H_T = available tower height. Further, L_i is length of the optical fiber entering the i^th turn as depicted using reference numeral 302, L_I+1 is length of the optical fiber exiting the i^th turn as depicted using reference numeral 306 and h_i is corresponding vertical drop of path entering the i^th turn as depicted using reference numeral 304.

Equation 3 - Bended path length for the multiple partial turns 120 within the idealized tower frame border, i.e., available tower width 308: $\cos \cos θ = \frac{2 H_{T}}{{NW}_{T}} [1 - (1 + p) \sin \sin θ]$ Where p = desired fractional increase in draw path length, N = number of turn segments required to cover the vertical drop 304, H_T = available tower height and W_T = available tower width.

The above equations show the constraint if the optical fiber production is restricted to a horizontal dimension of W_T given a vertical drop of h_i and a desired fractional increase of p in the path length.

After exiting the plurality of air knives 112, the optical fiber 106 may be directed for further controlled cooling or directed to other processing units for such as but not limited to coating, spooling.

In accordance with an embodiment of the present disclosure, the plurality of air knives 112 with bending angle less than 90 degrees can be accommodated in existing draw tower constraint that allows sequential turning of the optical fiber 106 at predefined angles i.e., less than 90 degrees in a predefined draw tower volume which further increases the residence time and annealing/dwell time within a standard draw tower height and width as shown using the above equations. Resultantly, one can achieve the optical fiber 106 within required fictive temperature and attenuation values (for example, 0.17 dB/km-0.18dB/km) without dimensionally changing the existing draw tower set-up. In general, the fictive temperature is the temperature at which corresponding liquid structure and properties of glass are frozen in upon cooling and the attenuation corresponds to signal loss.

Fig. 4 is a flow chart representing a method of drawing the optical fiber 106 in the optical fiber draw tower 100 in accordance with an embodiment of the present disclosure.

At step 402, the method includes drawing the optical fiber 106 from the preform 104.

At step 404, the method includes modifying the vertical path length of the optical fiber 106 by subsequent partial turns, wherein the bended path length is defined by laminar flow for at least 70% of the bended path length, thereby modifying the vertical path length of the optical fiber 106 into the bended path length. In this step, the plurality of air knives 112 modifies the vertical path length taken by the optical fiber 106 (in melted state) due to gravity by subsequent partial turns. In particular, such modification in the vertical path length is done by applying external force to the optical fiber (uncooled optical fiber) at the one or more predefined zones 114, 116, 118 in the optical fiber draw tower 100 and by altering path of the fluid at the one or more predefined zones 114, 116, 118 in the optical fiber draw tower 100 due to application of the external force which causes the optical fiber in uncooled state to deviate from the vertical path into the bended path. The external force to the optical fiber in uncooled state is applied by at least one of adding or removing the fluid mass from the optical fiber draw tower 100 in the one or more predefined zones 114, 116, 118 such that the optical fiber bends subsequently in the partial turns.

It may be noted that the flow chart 400 is explained to have above stated process steps; however, those skilled in the art would appreciate that the flow chart 400 may have more/less number of process steps which may enable all the above stated implementations of the present disclosure.

A person of ordinary skill in the art may be aware that, in combination with the examples described in the embodiments disclosed in this specification, units and algorithm steps may be implemented by electronic hardware, computer software, or a combination thereof.

The foregoing descriptions of specific embodiments of the present technology have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present technology to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present technology and its practical application, to thereby enable others skilled in the art to best utilize the present technology and various embodiments with various modifications as are suited to the particular use contemplated.

Disjunctive language such as the phrase "at least one of X, Y, Z," unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y, or at least one of Z to each be present.

In a case that no conflict occurs, the embodiments in the present disclosure and the features in the embodiments may be mutually combined. The protection scope of the present disclosure shall be subject to the protection scope of the claims.

An optical fiber draw tower (100) configured to melt a preform (104) into an optical fiber (106) characterized in that: a top end zone (108) and a bottom end zone (110), wherein the preform (104) is inserted at the top end zone (108) and is melted into the optical fiber (106) that exits from the bottom end zone (110), wherein a fluid is inserted into the optical fiber draw tower (100) from the top end zone (108); and

a plurality of air knives ( 112) that distorts an optical fiber path such that partially uncooled optical fiber deviates from a vertical path and follows a bended path, wherein the plurality of air knives (112) include a plurality of openings arranged such that to cause distortion on the vertical path of the optical fiber (106) in the optical fiber draw tower (100), wherein the plurality of openings is a combination of one or more of a suction and pumping of the fluid;

wherein a bended path length is greater than a vertical path length, wherein the bended path length is defined by laminar flow for at least 70% of the bended path length.

The optical fiber draw tower (100) as claimed in claim 1, wherein the plurality of air knives (112) modifies mass flow of the fluid in a predefined manner to modify the optical fiber path inside the optical fiber draw tower (100).

The optical fiber draw tower (100) as claimed in claim 1, wherein the plurality of air knives (112) is arranged such that the fluid enters or exits the optical fiber draw tower (100) at an angle of 0-89 degrees with respect to the vertical path.

The optical fiber draw tower (100) as claimed in claim 1, wherein the bended path length is at least 10% greater than the vertical path length of the optical fiber (106).

The optical fiber draw tower (100) as claimed in claim 1, wherein the bended path length for a single partial turn is defined by:

0 A = OU = 0 Q = r

AQ = 2 Δ = 2 r \cos \cos θ

where A= entrance path (202) of the optical fiber (106) and Q = exit path (204) of the optical fiber (106).

The optical fiber draw tower (100) as claimed in claim 1, wherein the bended path length for multiple partial turns is defined by:

\sum_{i = 1}^{N} h_{i} + \sum_{i = 1}^{N} Δ_{i} = H_{T}

\sum_{i = 1}^{N} L_{i} = H_{T} (1 + p)

where p = desired fractional increase in draw path length, N = number of turn segments required to cover a vertical drop (304), HT = available tower height, Li= length of the optical fiber (106) entering i^th turn, Li+1 = length of the optical fiber (106) exiting the i^th turn and hi = corresponding vertical drop of path entering the i^th turn.

The optical fiber draw tower (100) as claimed in claim 1, wherein the bended path length for multiple partial turns is defined by: cos cos Θ =

\frac{2 H_{T}}{{NW}_{T}} [1 - (1 + p) \sin \sin θ]

where p = desired fractional increase in draw path length, N = number of turn segments required to cover the vertical drop (304), HT = available tower height and WT = available tower width.

A method of drawing an optical fiber (106) in an optical fiber draw tower (100),
characterized in that steps of: drawing the optical fiber (106) from a preform (104); and

modifying a vertical path length of the optical fiber (106) by subsequent partial turns, enabled by plurality of air knives (112),

wherein the plurality of air knives (112) include a plurality of openings arranged such that to cause distortion on the vertical path of the optical fiber (106) in the optical fiber draw tower (100), wherein the plurality of openings is a combination of one or more of a suction and pumping of the fluid;

wherein a bended path length is defined by laminar flow for at least 70% of the bended path length, thereby modifying the vertical path length of the optical fiber (106) into the bended path length.

The method as claimed in 8, 10, wherein the bended path length for a single partial turn is defined by:

\begin{array}{l} AQ = 2 Δ = 2 r \cos \\ 0 A = OU = 0 Q = r \\ \cos ⊖ \end{array}

where A = entrance path (202) of the optical fiber (106) and Q = exit path (204) of the optical fiber (106).

The method as claimed in claim 8, wherein the bended path length for multiple partial turns is defined by:

\sum_{i = 1}^{N} h_{i} + \sum_{i = 1}^{N} Δ_{i} = H_{T}

\sum_{i = 1}^{N} L_{i} = H_{T} (1 + p)

where p = desired fractional increase in draw path length, N = number of turn segments required to cover a vertical drop (304), HT = available tower height, Li= length of the optical fiber (106) entering i^th turn, Li+1 = length of the optical fiber (106) exiting the i^th turn and hi= corresponding vertical drop of path entering the i^th tum;

The method as claimed in claim 8, wherein the bended path length for multiple partial turns is defined by:

\cos \cos θ = \frac{2 H_{T}}{{NW}_{T}} [1 - (1 + p) \sin \sin θ]

where p = desired fractional increase in draw path length, N = number of turn segments required to cover the vertical drop (304), HT= available tower height and WT = available tower width.

The method as claimed in claim 8, wherein modifying the vertical path length of the optical fiber (106) by the subsequent partial turns further comprising: applying external force to uncooled optical fiber at one or more predefined zones (114, 116, 118) in the optical fiber draw tower (100); and

altering path of a fluid at the one or more predefined zones (114, 116, 118) in the optical fiber draw tower (100) due to application of the external force causing the uncooled optical fiber to deviate from the vertical path into a bended path.

The method as claimed in claim 9, wherein applying the external force to the uncooled optical fiber comprising at least one of adding or removing fluid mass from the optical fiber draw tower (100) in the one or more predefined zones (114, 116, 118) such that the optical fiber (106) bends subsequently in partial turns, thereby modifying the vertical path length to a bended path length.

Glasfaserziehturm (100), der so konfiguriert ist, dass er einen Vorformling (104) zu einer Glasfaser (106) schmilzt, dadurch gekennzeichnet, dass: eine obere Endzone (108) und eine untere Endzone (110), wobei der Vorformling (104) an der oberen Endzone (108) eingeführt und in die Glasfaser (106) eingeschmolzen wird, die aus der unteren Endzone (110) austritt, wobei ein Fluid von der oberen Endzone (108) in den Glasfaserziehturm (100) eingeführt wird; und

eine Vielzahl von Luftmessern (112), die einen Glasfaserpfad so verzerren, dass ein teilweise ungekühlter Glasfaser von einem vertikalen Pfad abweicht und einem gebogenen Pfad folgt,

wobei die Vielzahl von Luftmessern (112) eine Vielzahl von Öffnungen umfasst, die so angeordnet sind, dass sie eine Verzerrung auf dem vertikalen Pfad der Glasfaser (106) im Glasfaserziehturm (100) verursachen, wobei die Vielzahl von Öffnungen eine Kombination aus einem oder mehreren Ansaugen und Pumpen des Fluids ist;

wobei eine Länge des gebogenen Pfads größer als eine Länge des vertikalen Pfads ist, wobei die Länge des gebogenen Pfads für mindestens 70 % der Länge des gebogenen Pfads durch eine laminare Strömung definiert ist.

Glasfaserziehturm (100) nach Anspruch 1, wobei die Vielzahl von Luftmessern (112) den Massenstrom des Fluids in einer vorgegebenen Weise modifiziert, um den Glasfaserpfad im Inneren des Glasfaserziehturms (100) zu modifizieren.

Glasfaserziehturm (100) nach Anspruch 1, wobei die Vielzahl von Luftmessern (112) so angeordnet ist, dass das Fluid in einem Winkel von 0 bis 89 Grad in Bezug auf den vertikalen Pfad in den Glasfaserziehturm (100) eintritt oder aus diesem austritt.

Glasfaserziehturm (100) nach Anspruch 1, wobei die Länge des gebogenen Pfads mindestens 10 % größer als die Länge des vertikalen Pfads der Glasfaser (106) ist.

Glasfaserziehturm (100) nach Anspruch 1, wobei die Länge des gebogenen Pfads für eine einzelne Teilwindung definiert ist durch:

0 A = OU = 0 Q = r

AQ = 2 Δ = 2 r \cos \cos θ

wobei A = Eingangspfad (202) der Glasfaser (106) und Q = Ausgangspfad (204) der Glasfaser (106).

Glasfaserziehturm (100) nach Anspruch 1, wobei die Länge des gebogenen Pfads für mehrere Teilwindungen definiert ist durch:

\sum_{i = 1}^{N} h_{i} + \sum_{i = 1}^{N} Δ_{i} = H_{T}

\sum_{i = 1}^{N} L_{i} = H_{T} (1 + p)

wobei p = gewünschte fraktionelle Zunahme der Zugpfadlänge, N = Anzahl der erforderlichen Windungssegmente, um einen vertikalen Abfall (304) abzudecken, HT = verfügbare Turmhöhe, Li = Länge der Glasfaser (106), die in die i^te Windung eintritt, Li+1 = Länge der Glasfaser (106), die aus der i^ten Windung austritt, und hi = entsprechender vertikaler Abfall des Pfads, der in die i^te Windung eintritt.

Glasfaserziehturm (100) nach Anspruch 1, wobei die Länge des gebogenen Pfads für mehrere Teilwindungen definiert ist durch: cos cos Θ =

\frac{2 H_{T}}{{NW}_{T}} [1 - (1 + p) \sin \sin θ]

wobei p = gewünschte fraktionelle Zunahme der Zugpfadlänge, N = Anzahl der erforderlichen Windungssegmente, um den vertikalen Abfall (304) abzudecken, HT = verfügbare Turmhöhe und WT = verfügbare Turmbreite.

Verfahren zum Ziehen einer Glasfaser (106) in einem Glasfaserziehturm (100), gekennzeichnet durch die Schritte: Ziehen der Glasfaser (106) aus einem Vorformling (104); und

Modifizieren einer Länge des vertikalen Pfads der Glasfaser (106) durch nachfolgende Teilwindungen, ermöglicht durch eine Vielzahl von Luftmessern (112),

wobei eine Länge des gebogenen Pfads durch eine laminare Strömung für mindestens 70 % der Länge des gebogenen Pfads definiert ist, wodurch die Länge des vertikalen Pfads der Glasfaser (106) in die Länge des gebogenen Pfads modifiziert wird.

Verfahren nach Anspruch 8, wobei die Länge des gebogenen Pfads für eine einzelne Teilwindung definiert ist durch:

0 A = OU = 0 Q = r AQ = 2 Δ = 2 r \cos \cos Θ

wobei A = Eingangspfad (202) der Glasfaser (106) und Q = Ausgangspfad (204) der Glasfaser (106).

Verfahren nach Anspruch 8, wobei die Länge des gebogenen Pfads für mehrere Teilwindungen definiert ist durch:

\sum_{i = 1}^{N} h_{i} + \sum_{i = 1}^{N} Δ_{i} = H_{T}

\sum_{i = 1}^{N} L_{i} = H_{T} (1 + p)

Verfahren nach Anspruch 8, wobei die Länge des gebogenen Pfads für mehrere Teilwindungen definiert ist durch:

\cos \cos θ = \frac{2 H_{T}}{{NW}_{T}} [1 - (1 + p) \sin \sin θ]

Verfahren nach Anspruch 8, wobei die Modifizierung der Länge des vertikalen Pfads der Glasfaser (106) durch die nachfolgenden Teilwindungen ferner umfasst: Aufbringen einer externen Kraft auf eine ungekühlte Glasfaser an einer oder mehreren vordefinierten Zonen (114, 116, 118) im Glasfaserziehturm (100); und

Verändern des Pfads eines Fluides an einer oder mehreren vordefinierten Zonen (114, 116, 118) im Glasfaserziehturm (100) aufgrund des Aufbringen der externen Kraft, wodurch die ungekühlte Glasfaser von dem vertikalen Pfad in einen gebogenen Pfad abweicht.

Verfahren nach Anspruch 9, wobei Aufbringen der externen Kraft auf die ungekühlte Glasfaser das Hinzufügen oder Entfernen von Fluidmasse aus dem Glasfaserziehturm (100) in einer oder mehreren vordefinierten Zonen (114, 116, 118) umfasst, so dass sich die Glasfaser (106) anschließend in Teilwindungen biegt, wodurch die Länge des vertikalen Pfads in eine Länge des gebogenen Pfads modifiziert wird.

Tour d'étirage de fibre optique (100) configurée pour fondre une préforme (104) en une fibre optique (106) caractérisée en ce que : une zone d'extrémité supérieure (108) et une zone d'extrémité inférieure (110), dans laquelle la préforme (104) est insérée au niveau de la zone d'extrémité supérieure (108) et est fondue en la fibre optique (106) qui sort de la zone d'extrémité inférieure (110), dans laquelle un fluide est inséré dans la tour d'étirage de fibre optique (100) à partir de la zone d'extrémité supérieure (108) ; et

une pluralité de lames d'air (112) qui déforme un trajet de fibre optique de sorte que la fibre optique partiellement non refroidie s'écarte d'un trajet vertical et suive un trajet courbé,

dans laquelle la pluralité de lames d'air (112) comporte une pluralité d'ouvertures agencées de manière à provoquer une distorsion sur le trajet vertical de la fibre optique (106) dans la tour d'étirage de fibre optique (100), dans laquelle la pluralité d'ouvertures est une combinaison d'une ou plusieurs parmi une aspiration et un pompage du fluide ;

dans laquelle une longueur de trajet courbé est supérieure à une longueur de trajet vertical, la longueur de trajet courbé étant définie par un écoulement laminaire pour au moins 70 % de la longueur de trajet courbé.

Tour d'étirage de fibre optique (100) selon la revendication 1, dans laquelle la pluralité de lames d'air (112) modifie l'écoulement massique du fluide d'une manière prédéfinie pour modifier le trajet de fibre optique à l'intérieur de la tour d'étirage de fibre optique (100).

Tour d'étirage de fibre optique (100) selon la revendication 1, dans laquelle la pluralité de lames d'air (112) est agencée de sorte que le fluide entre ou sorte de la tour d'étirage de fibre optique (100) à un angle de 0 à 89 degrés par rapport au trajet vertical.

Tour d'étirage de fibre optique (100) selon la revendication 1, dans laquelle la longueur de trajet courbé est au moins 10 % supérieure à la longueur de trajet vertical de la fibre optique (106).

Tour d'étirage de fibre optique (100) selon la revendication 1, dans laquelle la longueur de trajet courbé pour un seul tournant partiel est définie par :

0 A = OU = 0 Q = r

AQ = 2 Δ = 2 r \cos \cos θ

où A = trajet d'entrée (202) de la fibre optique (106) et Q = trajet de sortie (204) de la fibre optique (106).

Tour d'étirage de fibre optique (100) selon la revendication 1, dans laquelle la longueur de trajet courbé pour plusieurs tournants partiels est définie par :

\sum_{i = 1}^{N} h_{i} + \sum_{i = 1}^{N} Δ_{i} = H_{T}

\sum_{i = 1}^{N} L_{i} = H_{T} (1 + p)

où p = augmentation fractionnelle souhaitée de la longueur du trajet d'étirage, N = nombre de segments de tournant requis pour couvrir une chute verticale (304), HT = hauteur de tour disponible, Li = longueur de la fibre optique (106) entrant dans le i^ème tournant, Li+1 = longueur de la fibre optique (106) sortant du i^ème tournant et hi = chute verticale correspondante de trajet entrant dans le i^ème tournant.

Tour d'étirage de fibre optique (100) selon la revendication 1, dans laquelle la longueur de trajet courbé pour plusieurs tournants partiels est définie par : cos cos Θ =

\frac{2 H_{T}}{{NW}_{T}} [1 - (1 + p) \sin \sin θ]

où p = augmentation fractionnelle souhaitée de la longueur du trajet d'étirage, N = nombre de segments de tournant requis pour couvrir la chute verticale (304), HT = hauteur de tour disponible et WT = largeur de tour disponible.

Procédé d'étirage d'une fibre optique (106) dans une tour d'étirage de fibre optique (100), caractérisé par les étapes suivantes : étirage de la fibre optique (106) à partir d'une préforme (104) ; et

modification d'une longueur de trajet vertical de la fibre optique (106) par des tournants partiels successifs, activés par une pluralité de lames d'air (112),

dans lequel une longueur de trajet courbé est définie par un écoulement laminaire pour au moins 70 % de la longueur de trajet courbé, modifiant ainsi la longueur de trajet vertical de la fibre optique (106) en longueur de trajet courbé.

Procédé selon la revendication 8, dans lequel la longueur de trajet courbé pour un seul tournant partiel est définie par :

0 A = OU = 0 Q = r AQ = 2 Δ = 2 r \cos cosΘ

où A = trajet d'entrée (202) de la fibre optique (106) et Q = trajet de sortie (204) de la fibre optique (106).

Procédé selon la revendication 8, dans lequel la longueur de trajet courbé pour plusieurs tournants partiels est définie par :

\sum_{i = 1}^{N} h_{j} + \sum_{i = 1}^{N} Δ_{i} = H_{T}

\sum_{i = 1}^{N} L_{i} = H_{T} (1 + p)

Procédé selon la revendication 8, dans lequel la longueur de trajet courbé pour plusieurs tournants partiels est définie par :

\cos \cos θ = \frac{2 H_{T}}{{NW}_{T}} [1 - (1 + p) \sin \sin θ]

Procédé selon la revendication 8, dans lequel la modification de la longueur de trajet vertical de la fibre optique (106) par les tournants partiels successifs comprend en outre : l'application d'une force externe à une fibre optique non refroidie au niveau d'une ou plusieurs zones prédéfinies (114, 116, 118) dans la tour d'étirage de fibre optique (100) ; et

la modification du trajet d'un fluide au niveau des une ou plusieurs zones prédéfinies (114, 116, 118) dans la tour d'étirage de fibre optique (100) en raison de l'application de la force externe entraînant la déviation de la fibre optique non refroidie du trajet vertical vers un trajet courbé.

Procédé selon la revendication 9, dans lequel l'application de la force externe à la fibre optique non refroidie comprend au moins l'un parmi un ajout ou une élimination de masse de fluide de la tour d'étirage de fibre optique (100) dans les une ou plusieurs zones prédéfinies (114, 116, 118) de sorte que la fibre optique (106) se courbe ensuite en tournants partiels, modifiant ainsi la longueur de trajet vertical en une longueur de trajet courbé.

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

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